The present invention relates to couplers used to secure attachments such as buckets, impact hammers, shears, etc. fixedly and operatively to the distal end of an arm of a tractor, backhoe, excavator or other type of arm-equipped construction/agricultural equipment. As is generally well known, couplers, also referred to as “quick couplers,” are used as an alternative to a pin-on connection for fixedly and operatively securing an attachment to the distal end of an arm which is, in turn, secured to a boom of a construction/agricultural machine such as a backhoe or excavator.
Spread-style couplers are generally known. These couplers are connected to an arm by a pin-on connection at a first pivot point and are connected to a control link by a pin-on connection at a second pivot point. These prior couplers include first and second hooks that open in opposite directions oriented outwardly away from each other. In use, the hooks are collapsed toward each other are placed between first and second pins of a bucket or other attachment and the hooks are then spread-apart from each other, using a screw jack, hydraulic cylinder or other means. Upon being spread sufficiently far apart, the first hook engages the first pin of the attachment and the second hook engages the second pin of the attachment which results in the attachment being operatively connected to the arm.
It has been deemed desirable to provide a spread-style coupler with a supplemental lock system that prevents undesired attachment decoupling when the coupler is not located in a proper decoupling position. Specifically, for safety, it has been deemed desirable to provide a spread-style coupler with a mechanical supplemental lock system that prevents attachment decoupling unless the coupler is curled sufficiently relative to the machine arm so that the attachment cannot fall uncontrollably from the coupler upon movement of the first and second hooks inwardly toward each other.